1 // SPDX-License-Identifier: GPL-2.0-only
6 * o allow users to set the parameters
7 * o sync/async switching ?
9 * Note: This does _not_ implement CCITT X.25 asynchronous framing
10 * recommendations. Its primarily for testing purposes. If you wanted
11 * to do CCITT then in theory all you need is to nick the HDLC async
12 * checksum routines from ppp.c
15 * 2000-10-29 Henner Eisen lapb_data_indication() return status.
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 #include <linux/module.h>
22 #include <linux/uaccess.h>
23 #include <linux/bitops.h>
24 #include <linux/string.h>
26 #include <linux/interrupt.h>
28 #include <linux/tty.h>
29 #include <linux/errno.h>
30 #include <linux/netdevice.h>
31 #include <linux/etherdevice.h>
32 #include <linux/skbuff.h>
33 #include <linux/if_arp.h>
34 #include <linux/lapb.h>
35 #include <linux/init.h>
36 #include <linux/rtnetlink.h>
37 #include <linux/slab.h>
38 #include <net/x25device.h>
41 static struct net_device
**x25_asy_devs
;
42 static int x25_asy_maxdev
= SL_NRUNIT
;
44 module_param(x25_asy_maxdev
, int, 0);
45 MODULE_LICENSE("GPL");
47 static int x25_asy_esc(unsigned char *p
, unsigned char *d
, int len
);
48 static void x25_asy_unesc(struct x25_asy
*sl
, unsigned char c
);
49 static void x25_asy_setup(struct net_device
*dev
);
51 /* Find a free X.25 channel, and link in this `tty' line. */
52 static struct x25_asy
*x25_asy_alloc(void)
54 struct net_device
*dev
= NULL
;
58 if (x25_asy_devs
== NULL
)
59 return NULL
; /* Master array missing ! */
61 for (i
= 0; i
< x25_asy_maxdev
; i
++) {
62 dev
= x25_asy_devs
[i
];
68 sl
= netdev_priv(dev
);
70 if (!test_and_set_bit(SLF_INUSE
, &sl
->flags
))
75 /* Sorry, too many, all slots in use */
76 if (i
>= x25_asy_maxdev
)
79 /* If no channels are available, allocate one */
82 sprintf(name
, "x25asy%d", i
);
84 dev
= alloc_netdev(sizeof(struct x25_asy
), name
,
85 NET_NAME_UNKNOWN
, x25_asy_setup
);
89 /* Initialize channel control data */
90 sl
= netdev_priv(dev
);
93 /* register device so that it can be ifconfig'ed */
94 if (register_netdev(dev
) == 0) {
95 /* (Re-)Set the INUSE bit. Very Important! */
96 set_bit(SLF_INUSE
, &sl
->flags
);
97 x25_asy_devs
[i
] = dev
;
100 pr_warn("%s(): register_netdev() failure\n", __func__
);
108 /* Free an X.25 channel. */
109 static void x25_asy_free(struct x25_asy
*sl
)
111 /* Free all X.25 frame buffers. */
117 if (!test_and_clear_bit(SLF_INUSE
, &sl
->flags
))
118 netdev_err(sl
->dev
, "x25_asy_free for already free unit\n");
121 static int x25_asy_change_mtu(struct net_device
*dev
, int newmtu
)
123 struct x25_asy
*sl
= netdev_priv(dev
);
124 unsigned char *xbuff
, *rbuff
;
128 xbuff
= kmalloc(len
+ 4, GFP_ATOMIC
);
129 rbuff
= kmalloc(len
+ 4, GFP_ATOMIC
);
131 if (xbuff
== NULL
|| rbuff
== NULL
) {
137 spin_lock_bh(&sl
->lock
);
138 xbuff
= xchg(&sl
->xbuff
, xbuff
);
140 if (sl
->xleft
<= len
) {
141 memcpy(sl
->xbuff
, sl
->xhead
, sl
->xleft
);
144 dev
->stats
.tx_dropped
++;
147 sl
->xhead
= sl
->xbuff
;
149 rbuff
= xchg(&sl
->rbuff
, rbuff
);
151 if (sl
->rcount
<= len
) {
152 memcpy(sl
->rbuff
, rbuff
, sl
->rcount
);
155 dev
->stats
.rx_over_errors
++;
156 set_bit(SLF_ERROR
, &sl
->flags
);
163 spin_unlock_bh(&sl
->lock
);
171 /* Set the "sending" flag. This must be atomic, hence the ASM. */
173 static inline void x25_asy_lock(struct x25_asy
*sl
)
175 netif_stop_queue(sl
->dev
);
179 /* Clear the "sending" flag. This must be atomic, hence the ASM. */
181 static inline void x25_asy_unlock(struct x25_asy
*sl
)
183 netif_wake_queue(sl
->dev
);
186 /* Send an LAPB frame to the LAPB module to process. */
188 static void x25_asy_bump(struct x25_asy
*sl
)
190 struct net_device
*dev
= sl
->dev
;
196 dev
->stats
.rx_bytes
+= count
;
198 skb
= dev_alloc_skb(count
);
200 netdev_warn(sl
->dev
, "memory squeeze, dropping packet\n");
201 dev
->stats
.rx_dropped
++;
204 skb_put_data(skb
, sl
->rbuff
, count
);
205 skb
->protocol
= x25_type_trans(skb
, sl
->dev
);
206 err
= lapb_data_received(skb
->dev
, skb
);
207 if (err
!= LAPB_OK
) {
209 printk(KERN_DEBUG
"x25_asy: data received err - %d\n", err
);
211 dev
->stats
.rx_packets
++;
215 /* Encapsulate one IP datagram and stuff into a TTY queue. */
216 static void x25_asy_encaps(struct x25_asy
*sl
, unsigned char *icp
, int len
)
219 int actual
, count
, mtu
= sl
->dev
->mtu
;
222 /* Sigh, shouldn't occur BUT ... */
224 printk(KERN_DEBUG
"%s: truncating oversized transmit packet!\n",
226 sl
->dev
->stats
.tx_dropped
++;
232 count
= x25_asy_esc(p
, sl
->xbuff
, len
);
234 /* Order of next two lines is *very* important.
235 * When we are sending a little amount of data,
236 * the transfer may be completed inside driver.write()
237 * routine, because it's running with interrupts enabled.
238 * In this case we *never* got WRITE_WAKEUP event,
239 * if we did not request it before write operation.
240 * 14 Oct 1994 Dmitry Gorodchanin.
242 set_bit(TTY_DO_WRITE_WAKEUP
, &sl
->tty
->flags
);
243 actual
= sl
->tty
->ops
->write(sl
->tty
, sl
->xbuff
, count
);
244 sl
->xleft
= count
- actual
;
245 sl
->xhead
= sl
->xbuff
+ actual
;
247 clear_bit(SLF_OUTWAIT
, &sl
->flags
); /* reset outfill flag */
251 * Called by the driver when there's room for more data. If we have
252 * more packets to send, we send them here.
254 static void x25_asy_write_wakeup(struct tty_struct
*tty
)
257 struct x25_asy
*sl
= tty
->disc_data
;
259 /* First make sure we're connected. */
260 if (!sl
|| sl
->magic
!= X25_ASY_MAGIC
|| !netif_running(sl
->dev
))
263 if (sl
->xleft
<= 0) {
264 /* Now serial buffer is almost free & we can start
265 * transmission of another packet */
266 sl
->dev
->stats
.tx_packets
++;
267 clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
272 actual
= tty
->ops
->write(tty
, sl
->xhead
, sl
->xleft
);
277 static void x25_asy_timeout(struct net_device
*dev
, unsigned int txqueue
)
279 struct x25_asy
*sl
= netdev_priv(dev
);
281 spin_lock(&sl
->lock
);
282 if (netif_queue_stopped(dev
)) {
283 /* May be we must check transmitter timeout here ?
284 * 14 Oct 1994 Dmitry Gorodchanin.
286 netdev_warn(dev
, "transmit timed out, %s?\n",
287 (tty_chars_in_buffer(sl
->tty
) || sl
->xleft
) ?
288 "bad line quality" : "driver error");
290 clear_bit(TTY_DO_WRITE_WAKEUP
, &sl
->tty
->flags
);
293 spin_unlock(&sl
->lock
);
296 /* Encapsulate an IP datagram and kick it into a TTY queue. */
298 static netdev_tx_t
x25_asy_xmit(struct sk_buff
*skb
,
299 struct net_device
*dev
)
301 struct x25_asy
*sl
= netdev_priv(dev
);
304 if (!netif_running(sl
->dev
)) {
305 netdev_err(dev
, "xmit call when iface is down\n");
310 /* There should be a pseudo header of 1 byte added by upper layers.
311 * Check to make sure it is there before reading it.
318 switch (skb
->data
[0]) {
321 case X25_IFACE_CONNECT
: /* Connection request .. do nothing */
322 err
= lapb_connect_request(dev
);
324 netdev_err(dev
, "lapb_connect_request error: %d\n",
328 case X25_IFACE_DISCONNECT
: /* do nothing - hang up ?? */
329 err
= lapb_disconnect_request(dev
);
331 netdev_err(dev
, "lapb_disconnect_request error: %d\n",
338 skb_pull(skb
, 1); /* Remove control byte */
340 * If we are busy already- too bad. We ought to be able
341 * to queue things at this point, to allow for a little
342 * frame buffer. Oh well...
343 * -----------------------------------------------------
344 * I hate queues in X.25 driver. May be it's efficient,
345 * but for me latency is more important. ;)
347 * 14 Oct 1994 Dmitry Gorodchanin.
350 err
= lapb_data_request(dev
, skb
);
351 if (err
!= LAPB_OK
) {
352 netdev_err(dev
, "lapb_data_request error: %d\n", err
);
361 * LAPB interface boilerplate
365 * Called when I frame data arrive. We add a pseudo header for upper
366 * layers and pass it to upper layers.
369 static int x25_asy_data_indication(struct net_device
*dev
, struct sk_buff
*skb
)
371 if (skb_cow(skb
, 1)) {
376 skb
->data
[0] = X25_IFACE_DATA
;
378 skb
->protocol
= x25_type_trans(skb
, dev
);
380 return netif_rx(skb
);
384 * Data has emerged from the LAPB protocol machine. We don't handle
385 * busy cases too well. Its tricky to see how to do this nicely -
386 * perhaps lapb should allow us to bounce this ?
389 static void x25_asy_data_transmit(struct net_device
*dev
, struct sk_buff
*skb
)
391 struct x25_asy
*sl
= netdev_priv(dev
);
393 spin_lock(&sl
->lock
);
394 if (netif_queue_stopped(sl
->dev
) || sl
->tty
== NULL
) {
395 spin_unlock(&sl
->lock
);
396 netdev_err(dev
, "tbusy drop\n");
400 /* We were not busy, so we are now... :-) */
403 dev
->stats
.tx_bytes
+= skb
->len
;
404 x25_asy_encaps(sl
, skb
->data
, skb
->len
);
407 spin_unlock(&sl
->lock
);
411 * LAPB connection establish/down information.
414 static void x25_asy_connected(struct net_device
*dev
, int reason
)
416 struct x25_asy
*sl
= netdev_priv(dev
);
420 skb
= dev_alloc_skb(1);
422 netdev_err(dev
, "out of memory\n");
426 ptr
= skb_put(skb
, 1);
427 *ptr
= X25_IFACE_CONNECT
;
429 skb
->protocol
= x25_type_trans(skb
, sl
->dev
);
433 static void x25_asy_disconnected(struct net_device
*dev
, int reason
)
435 struct x25_asy
*sl
= netdev_priv(dev
);
439 skb
= dev_alloc_skb(1);
441 netdev_err(dev
, "out of memory\n");
445 ptr
= skb_put(skb
, 1);
446 *ptr
= X25_IFACE_DISCONNECT
;
448 skb
->protocol
= x25_type_trans(skb
, sl
->dev
);
452 static const struct lapb_register_struct x25_asy_callbacks
= {
453 .connect_confirmation
= x25_asy_connected
,
454 .connect_indication
= x25_asy_connected
,
455 .disconnect_confirmation
= x25_asy_disconnected
,
456 .disconnect_indication
= x25_asy_disconnected
,
457 .data_indication
= x25_asy_data_indication
,
458 .data_transmit
= x25_asy_data_transmit
,
462 /* Open the low-level part of the X.25 channel. Easy! */
463 static int x25_asy_open(struct net_device
*dev
)
465 struct x25_asy
*sl
= netdev_priv(dev
);
473 * Allocate the X.25 frame buffers:
475 * rbuff Receive buffer.
476 * xbuff Transmit buffer.
481 sl
->rbuff
= kmalloc(len
+ 4, GFP_KERNEL
);
482 if (sl
->rbuff
== NULL
)
484 sl
->xbuff
= kmalloc(len
+ 4, GFP_KERNEL
);
485 if (sl
->xbuff
== NULL
)
491 sl
->flags
&= (1 << SLF_INUSE
); /* Clear ESCAPE & ERROR flags */
493 netif_start_queue(dev
);
498 err
= lapb_register(dev
, &x25_asy_callbacks
);
513 /* Close the low-level part of the X.25 channel. Easy! */
514 static int x25_asy_close(struct net_device
*dev
)
516 struct x25_asy
*sl
= netdev_priv(dev
);
518 spin_lock(&sl
->lock
);
520 clear_bit(TTY_DO_WRITE_WAKEUP
, &sl
->tty
->flags
);
522 netif_stop_queue(dev
);
525 spin_unlock(&sl
->lock
);
530 * Handle the 'receiver data ready' interrupt.
531 * This function is called by the 'tty_io' module in the kernel when
532 * a block of X.25 data has been received, which can now be decapsulated
533 * and sent on to some IP layer for further processing.
536 static void x25_asy_receive_buf(struct tty_struct
*tty
,
537 const unsigned char *cp
, char *fp
, int count
)
539 struct x25_asy
*sl
= tty
->disc_data
;
541 if (!sl
|| sl
->magic
!= X25_ASY_MAGIC
|| !netif_running(sl
->dev
))
545 /* Read the characters out of the buffer */
548 if (!test_and_set_bit(SLF_ERROR
, &sl
->flags
))
549 sl
->dev
->stats
.rx_errors
++;
553 x25_asy_unesc(sl
, *cp
++);
558 * Open the high-level part of the X.25 channel.
559 * This function is called by the TTY module when the
560 * X.25 line discipline is called for. Because we are
561 * sure the tty line exists, we only have to link it to
562 * a free X.25 channel...
565 static int x25_asy_open_tty(struct tty_struct
*tty
)
570 if (tty
->ops
->write
== NULL
)
573 /* OK. Find a free X.25 channel to use. */
574 sl
= x25_asy_alloc();
580 tty
->receive_room
= 65536;
581 tty_driver_flush_buffer(tty
);
582 tty_ldisc_flush(tty
);
584 /* Restore default settings */
585 sl
->dev
->type
= ARPHRD_X25
;
587 /* Perform the low-level X.25 async init */
588 err
= x25_asy_open(sl
->dev
);
593 /* Done. We have linked the TTY line to a channel. */
599 * Close down an X.25 channel.
600 * This means flushing out any pending queues, and then restoring the
601 * TTY line discipline to what it was before it got hooked to X.25
602 * (which usually is TTY again).
604 static void x25_asy_close_tty(struct tty_struct
*tty
)
606 struct x25_asy
*sl
= tty
->disc_data
;
609 /* First make sure we're connected. */
610 if (!sl
|| sl
->magic
!= X25_ASY_MAGIC
)
614 if (sl
->dev
->flags
& IFF_UP
)
618 err
= lapb_unregister(sl
->dev
);
620 pr_err("%s: lapb_unregister error: %d\n",
623 tty
->disc_data
= NULL
;
628 /************************************************************************
629 * STANDARD X.25 ENCAPSULATION *
630 ************************************************************************/
632 static int x25_asy_esc(unsigned char *s
, unsigned char *d
, int len
)
634 unsigned char *ptr
= d
;
638 * Send an initial END character to flush out any
639 * data that may have accumulated in the receiver
643 *ptr
++ = X25_END
; /* Send 10111110 bit seq */
646 * For each byte in the packet, send the appropriate
647 * character sequence, according to the X.25 protocol.
654 *ptr
++ = X25_ESCAPE(X25_END
);
658 *ptr
++ = X25_ESCAPE(X25_ESC
);
669 static void x25_asy_unesc(struct x25_asy
*sl
, unsigned char s
)
674 if (!test_and_clear_bit(SLF_ERROR
, &sl
->flags
) &&
677 clear_bit(SLF_ESCAPE
, &sl
->flags
);
681 set_bit(SLF_ESCAPE
, &sl
->flags
);
683 case X25_ESCAPE(X25_ESC
):
684 case X25_ESCAPE(X25_END
):
685 if (test_and_clear_bit(SLF_ESCAPE
, &sl
->flags
))
689 if (!test_bit(SLF_ERROR
, &sl
->flags
)) {
690 if (sl
->rcount
< sl
->buffsize
) {
691 sl
->rbuff
[sl
->rcount
++] = s
;
694 sl
->dev
->stats
.rx_over_errors
++;
695 set_bit(SLF_ERROR
, &sl
->flags
);
700 /* Perform I/O control on an active X.25 channel. */
701 static int x25_asy_ioctl(struct tty_struct
*tty
, struct file
*file
,
702 unsigned int cmd
, unsigned long arg
)
704 struct x25_asy
*sl
= tty
->disc_data
;
706 /* First make sure we're connected. */
707 if (!sl
|| sl
->magic
!= X25_ASY_MAGIC
)
712 if (copy_to_user((void __user
*)arg
, sl
->dev
->name
,
713 strlen(sl
->dev
->name
) + 1))
719 return tty_mode_ioctl(tty
, file
, cmd
, arg
);
723 static int x25_asy_open_dev(struct net_device
*dev
)
725 struct x25_asy
*sl
= netdev_priv(dev
);
731 static const struct net_device_ops x25_asy_netdev_ops
= {
732 .ndo_open
= x25_asy_open_dev
,
733 .ndo_stop
= x25_asy_close
,
734 .ndo_start_xmit
= x25_asy_xmit
,
735 .ndo_tx_timeout
= x25_asy_timeout
,
736 .ndo_change_mtu
= x25_asy_change_mtu
,
739 /* Initialise the X.25 driver. Called by the device init code */
740 static void x25_asy_setup(struct net_device
*dev
)
742 struct x25_asy
*sl
= netdev_priv(dev
);
744 sl
->magic
= X25_ASY_MAGIC
;
746 spin_lock_init(&sl
->lock
);
747 set_bit(SLF_INUSE
, &sl
->flags
);
750 * Finish setting up the DEVICE info.
755 dev
->max_mtu
= 65534;
756 dev
->netdev_ops
= &x25_asy_netdev_ops
;
757 dev
->watchdog_timeo
= HZ
*20;
758 dev
->hard_header_len
= 0;
760 dev
->type
= ARPHRD_X25
;
761 dev
->tx_queue_len
= 10;
763 /* When transmitting data:
764 * first this driver removes a pseudo header of 1 byte,
765 * then the lapb module prepends an LAPB header of at most 3 bytes.
767 dev
->needed_headroom
= 3 - 1;
769 /* New-style flags. */
770 dev
->flags
= IFF_NOARP
;
773 static struct tty_ldisc_ops x25_ldisc
= {
774 .owner
= THIS_MODULE
,
775 .magic
= TTY_LDISC_MAGIC
,
777 .open
= x25_asy_open_tty
,
778 .close
= x25_asy_close_tty
,
779 .ioctl
= x25_asy_ioctl
,
780 .receive_buf
= x25_asy_receive_buf
,
781 .write_wakeup
= x25_asy_write_wakeup
,
784 static int __init
init_x25_asy(void)
786 if (x25_asy_maxdev
< 4)
787 x25_asy_maxdev
= 4; /* Sanity */
789 pr_info("X.25 async: version 0.00 ALPHA (dynamic channels, max=%d)\n",
792 x25_asy_devs
= kcalloc(x25_asy_maxdev
, sizeof(struct net_device
*),
797 return tty_register_ldisc(N_X25
, &x25_ldisc
);
801 static void __exit
exit_x25_asy(void)
803 struct net_device
*dev
;
806 for (i
= 0; i
< x25_asy_maxdev
; i
++) {
807 dev
= x25_asy_devs
[i
];
809 struct x25_asy
*sl
= netdev_priv(dev
);
811 spin_lock_bh(&sl
->lock
);
815 spin_unlock_bh(&sl
->lock
);
817 * VSV = if dev->start==0, then device
818 * unregistered while close proc.
820 unregister_netdev(dev
);
826 tty_unregister_ldisc(N_X25
);
829 module_init(init_x25_asy
);
830 module_exit(exit_x25_asy
);